This invention relates to a variable capacity wobble plate compressor for compressing refrigerant used in air conditioners for vehicles etc.
Conventional variables capacity wobble plate compressors of this kind have been proposed e.g. by Japanese Provisonal Utility Model Publication (Kokai) No. 64-4875, Japanese Provisional Patent Publication (Kokai) No. 63-140872, etc. which each comprise a drive shaft having opposite ends thereof rotatably supported by respective bearings, a wobble plate mounted on the drive shaft for swinging motion about the drive shaft, discharge valves each disposed to open to allow a refrigerant gas to be discharged into a discharge pressure chamber when pressure within a corresponding cylinder is above a predetermined value, a fixing member fixing the discharge valves in place, and a pressure-control valve arranged in a communicating passage extending between a suction chamber and a crankcase accommodating the wobble plate, for controlling pressure within the crankcase to adjust the inclination angle of the wobble plate, whereby the delivery quantity of capacity of the compressor is varied.
When the pressure-control valve is closed, pressure within the crankcase is inhibited from leaking into the suction chamber, so that high pressure gas leaking through clearances between cylinders and pistons, i.e. blow-by gas is accumulated within the crankcase to increase the pressure within the crankcase. As the pressure within the crankcase increases, the inclination angle of the wobble plate decreases to shorten the stroke of the pistons to thereby decrease the capacity of the compressor.
In these proposed variable capacity wobble plate compressors, for the purpose of compensating for insufficient pressure-increasing effect of the blow-by gas, a high pressure-introducing passage is provided for introducing high pressure from the discharge pressure chamber into the crankcase to thereby increase the pressure within the crankcase to a sufficient level.
However, in the conventional compressors, the high pressure-introducing passage is formed by providing through holes having the same diameter in a rear head, a valve plate, and a cylinder block, respectively, which makes the related parts complicated in construction and hence the machining thereof difficult to carry out.